title: A novel strategy to improve systemic oxygenation in venovenous extracorporeal membrane oxygenation: the "χ-configuration".
abstract: BACKGROUND
  Venovenous extracorporeal membrane oxygenation (VV-ECMO) is used in refractory acute respiratory distress syndrome where lung recovery is the primary goal. For its achievement, adequate extracorporeal blood flow and a maximal separation between oxygenated (inflow) and deoxygenated (outflow) blood flow are essential for reducing the recirculation phenomenon. We introduce the χ-configuration, a new cannulation strategy for VV-ECMO.
  
  
  METHODS
  We report our experience with 30 VV-ECMO consecutive patients: in 16 patients (group NS) we applied the χ-configuration, which consists of a particular right atrial cannula arrangement and a self-made modified inflow cannula, consisting of an outflow multihole venous cannula that was inserted percutaneously through the right femoral vein, into the right atrium, just below on the superior vena cava, and a self-made modified curved inflow cannula (inserted percutaneously through the right internal jugular vein) that, in its terminal segment, permitted the tip to be positioned close to the tricuspid valve. In 14 patients (group C) we applied the standard femoro-jugular VV-ECMO 2-cannula setting. In both groups, efficacy of blood oxygenation was obtained by gas-blood analysis, by blood samples obtained at arterial, central venous, and pulmonary artery lines, and by ECMO inflow and outflow lines. The recirculation fraction was obtained by a specific bedside formula.
  
  
  RESULTS
  No differences were noted between groups regarding the pre-ECMO patient characteristics. No complications during cannulation were recorded. In group NS, on-ECMO time, post-ECMO mechanical ventilation time, and ECMO overall results were significantly better than in group C. During high-flow VV-ECMO, pulmonary and systemic arterial oxygen saturation and arterial oxygen tension were significantly higher in group NS, and blood recirculation fraction was significantly lower.
  
  
  CONCLUSIONS
  Our data indicate that χ-configuration can be safe, feasible, and more effective than conventional VV-ECMO. It permits near complete drainage of the desaturated blood and a preferential oxygenated blood inflow toward the tricuspid valve, resulting in a significant reduction of recirculation, thereby improving the patient's oxygenation. Our innovative strategy reduces on-ECMO and post-ECMO mechanical ventilation time, gives a faster and better pulmonary recovery, improves survival, and can reduce hospital costs.
authors.affiliation: Cardiac Surgery, Medical and Surgical Critical Care Department, University of Florence, Firenze, Italy. mbonacchi@unifi.it
authors.forename: Massimo
authors.initials: M
authors.lastname: Bonacchi
authors.forename: Guy
authors.initials: G
authors.lastname: Harmelin
authors.forename: Adriano
authors.initials: A
authors.lastname: Peris
authors.forename: Guido
authors.initials: G
authors.lastname: Sani
mesh_terms: D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D016009:Chi-Square Distribution; D004867:Equipment Design; D015199:Extracorporeal Membrane Oxygenation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D010100:Oxygen